Digital scanning, or the recording of original images on sheets as digital image data, is familiar in the art of office equipment. In the case of a digital copier, facsimile, or other multifunction machine, a stack of sheets bearing images to be recorded as digital data (for subsequent printing as copies, or for facsimile or e-mail transmission) is loaded into the tray of a document handler, and then one sheet at a time is drawn therefrom and caused to move relative to an image sensor. Such an image sensor typically includes one or more linear arrays of photosensors, each photosensor recording the reflected light from a series of small areas in the original image as the image moves therepast, yielding a set of digital signals.
As a practical matter, the scanning of original images involves certain considerations to provide a satisfactory result. One set of considerations involves taking into account the size of the original documents being scanned. In a copying or faxing context, the size of the originals must be known or assumed so that resulting prints based on the data, such as copies or received faxes, are made on suitably-sized print sheets. As needed, the scanned image data may be reduced or enlarged (with software or hardware actions performed on the image data) so that the images are placed on a copy sheet of a known size. There is therefore a need to establish the size of the original sheets, and this is typically done either by having the user directly or indirectly enter the original size through a user interface, or by the copier or other machine accepting a signal related to the size of the stack, such as from a movable guide associated with the document handler.
A more complicated situation results from “mixed-size original” situations, where the stack associated with a single scanning or copying job includes sheets of two or more sizes. In such a case, individual sheets in the stack would each have different image sizes and therefore different optimal ways of handling each image, such as deciding whether or not to alter the size of the image in a subsequent copy.